A man has been charged with the murder of a 21-year-old inmate at Pentonville Prison.
Basana Kimbembi, 34, of no fixed abode, was charged on Friday following the death of Jamal Mahmoud on Tuesday.
Kimbembi will appear at court to face the murder charge at a later date.
A second man, aged 26, has been released from police custody and returned to prison, police said.
The Homicide and Major Crime Command unit are still investigating the incident.
Mahmoud died after being stabbed at the north London prison earlier this week.
Two other men - aged 21 and 30 - were taken to an east London hospital for treatment.
They remain in hospital but their injuries are not life threatening, police said.
A post-mortem examination which took place at Whittington Hospital on Thursday gave the cause of death as a stab wound.